Representatives of Luciano Pavarotti's two families were last night squaring up for a tussle after the publication of a second will leaving all of his property in the US to his second wife, Nicoletta Mantovani.

A lawyer representing the three daughters of his first marriage said he wanted an independent verification of the new document which, he said, appeared to be "seriously prejudicial" to their interests.

What no one knows is what share of the singer's estate is represented by his US assets. They have been valued at at least £10m. Reckonings of his overall worth range from over £130m down to £20m.

The opera star's first will - made in June and opened on September 7 - gave his daughters, including his youngest child by his second wife, only the legal minimum of one-eighth each.

A quarter went to Ms Mantovani directly. But, in addition, she was made sole beneficiary of a fund to take most of the remaining 25%.

The new, "special and limited last testament" opened on Monday and published yesterday by the news agency Ansa dealt with "all the goods, material and immaterial," owned by Pavarotti in the US.

They include three New York apartments, including one overlooking Central Park, and an art collection of unknown extent that contains at least one work by Henri Matisse. It was not immediately clear whether the new provisions applied to the tenor's future US royalties.

The second will, dated July 29, favoured Ms Mantovani on condition that she arranged for the inheritance to be put in a "qualified domestic trust". One purpose of a so-called QDT is to ensure that a surviving spouse does not pay US tax, but the benefit only applies if the widow or widower is a US citizen, which is not thought to be the case here.

Ms Mantovani's lawyer said the trust was set up in the weeks before his death. However, she added that the tenor had decided on the move months earlier.

Fabrizio Corsini, the three older daughters' lawyer, told the newspaper La Repubblica they had received the news of the first will "with utter calm". But, he said "now the matter takes on a different complexion". He added: "We want to check the documents properly - the date of the trust, and the [second] will [itself]. Then we shall be asking for an estimate of the estate - of the entire estate, including the American property. Then we shall see."